I primed the HS parts today. I changed my mind about using the water based primer and HVLP spray gun. I attended an RV Builders class and the instructor said using rattle cans is easy, quick, flexible and cost about the same. He said it takes 10 cans and the final extra weight will be 7 pounds and that is with painting the full skin surfaces. I painted all the frame parts and the rivet holes inside the skins. I used SEM Self Etching Primer. I setup a box so the over spray would go through and not bounce around. And I used the gas mask so my wife wouldn't think I was breathing in fumes. I cleaned all the parts with aluminum cleaner. I did not etch separately. The primer went on in 3 thin coats. Coverage was okay, but I need to slow down moving the can next time. It seems to be stuck on pretty good. It dries in 5 minutes to touch 24 hours solid. I used one whole can on the HS. I think this is going to take way more than 10 cans. I was not happy with the box arrangement and still got primer on shop floor. I need another idea.